Seth Thomas 48N making me crazy - stops after 4 days, help!

Discussion in 'Clock Repair' started by R. Croswell, Aug 30, 2017.

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  1. R. Croswell

    R. Croswell Registered User

    Apr 4, 2006
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    This Seth Thomas 48N is driving me nuts! It came in about two years ago and the owner said it wouldn't run a full week and a few other issues. One spring was busted and the other cracked so replaced both MS-210 0.016 x 60 on time train. Clock had previous work by others but no disasters. It was filthy so I cleaned it, did the pivots and a few bushings. Clock ran strong and was sent home. Then a few months ago it came back - owner couldn't keep it running. This is a crystal regulator case and the movement mounts with a "bayonet lock" insert - twist - tighten screw in the bottom. Screw is in a slotted hole and had slipped, perhaps from a strong-arm winding so movement was severely out of beat. I repositioned the movement, checked the beat and tightened the screw extra tight. I gave it a drop of oil and checked the beat, perfect. Pendulum swing good and it ran 12 days on test run so it went home again. Now its back after just a few months and the complaint is that it stops after 4 days. That the background info.

    So the owner set the clock on my unused kitchen table and it immediately began to free-run without the pendulum and did so for several days until it ran down. So while its waiting a turn on the bench I wind it fully and put on the pendulum to see if I can duplicate the problem, perhaps the owner just isn't winging it fully. It run great, nice pendulum swing, perfect in beat then just after the 4th day the sucker stopped. OK, so there is a problem, I just need to find it. So the hands are a bit close perhaps binding? So I give the hands a little more clearance. It stopped a little before the warning run. So I give the pendulum a little swing and it starts up fine and I think yes, that was it. Then in about 6 hours the sucker stopped again a few minutes after the hour, so probably not related to the clock setting up to strike. So I'm thinking I'm going to have to tear this thing apart again but I'll try starting it one more time. That was three days ago and it was still running fine when I just checked it, which makes a total of 7 days on that one winding. Tomorrow is day 4 after the restart and day 8 on that winding.

    So what the heck is happening on the 4th day that's stopping this clock? All the wheels rotate more than once in four days. Its still running strong after 7 days but can't seem to make it past mid week. I guess I'll tear it apart in a few days when it gets to the bench but not sure what I'm looking for. I can check all the usual suspects but just can't understand why the mid-week stoppage and then finishing the week running strong. Anyone ever encounter this or have any ideas?

    RC 314809.jpg
     
  2. Bruce Alexander

    Bruce Alexander Registered User
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    Interesting problem RC. Perhaps the four-day cycle is a red herring. What's the Strike Train and Snail doing during this time? Is the Gathering Pallet clearing the top of all Rack Teeth? The relation looks a little suspicious in your photo. Nice looking movement by the way. Was the photo taken after you serviced it?
     
  3. harold bain

    harold bain Registered User
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    RC, I had a similar problem with a ST Kaiser movement. Turned out the dial was too close to the hour arbor, just enough to rob power from the time train and stop the clock. Might run a few days before stopping. I cheated and filed the dial enough for clearance to get it working well.
     
  4. R. Croswell

    R. Croswell Registered User

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    Thanks, I'm making a note all the suggestions. I'm sure it will be something silly after it is discovered.

    RC
     
  5. kinsler33

    kinsler33 Registered User

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    #5 kinsler33, Aug 31, 2017
    Last edited: Aug 31, 2017
    This looks a lot like the 48J I inherited from my father, the clock collector. He sold off the whole inventory except for this one, and that's because it wouldn't run reliably. Drove me nuts for months: sometimes it would work, sometimes not. I opened out the bushings someone had installed on the time train, and replaced the time-side mainspring, and polished the pivots, and cleaned and cleaned and pegged and everything I could think of.

    Finally, for some reason I either don't remember or never knew, I bushed the pivots on the verge. Not too tightly, but I was apparently able to tighten it up enough. And from then on the clock's pendulum swing increased, its tick sounded healthier, and it hasn't stopped since, except when I forget to wind it.

    Now, I know that pivots high in the time train aren't supposed to ever need bushing, but I've discovered that bushing the verge and the escape wheel can often make a very large difference in the performance of an old movement. Any lost motion there is amplified.

    M Kinsler
     
  6. R. Croswell

    R. Croswell Registered User

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    Good thought. My records indicate that I did bush the escape wheel pivot holes but not the verge pivot holes. I'll take a closer look at those. Strange why it wants to stop mid-week but after two restarts within a few minutes it continues to run. Checked it a few minutes ago and still running OK on the 9th day. Perhaps the problem is random not a specific event on the 4th day. I plan to let it run down until it stops then rewind and see if it stops again on the 4th day. By that time the bench work should be cleared and I can dig into this one.......again.

    Bob
     
  7. Uhralt

    Uhralt Registered User
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    I would take a very close look at the mainspring. The spring seems to be the only thing of the movement that is in a unique position at day 4. Maybe there is something that causes it to bind for a short time and then binding is released shortly after. something like this could cause your problem. I once had a spring that had a very stiff section in about the middle of it that would hardly bend.

    Uhralt
     
  8. dad1891

    dad1891 Registered User

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    One thing that I would check is whether anything on a spring barrel is catching on a second wheel. I have seen one situation that when the strike spring barrel and the time second wheel lined up just right, they would rub an make an annoying sound. Would only do it when the barrel and the second wheel were lined up just right. It took me several months to find that one.....aargh!
     
  9. Tinker Dwight

    Tinker Dwight Registered User

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    First thing to do is to mark the wheels location with a sharpie each
    time it stops. I don't think it will show anything but you never know,
    it might be a bur on a tooth.
    What I think it is is the spring. Layers are sticking together.
    Next time you wind, let it down one turn. See if that makes a
    difference in run time.
    Slight differences in temper over the length can make a band
    of the spring more likely to have the layers stick.
    All just a guess so treat it as such.
    Tinker Dwight
     
  10. R. Croswell

    R. Croswell Registered User

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    Uhralt

    Good thought. I once had a movement where there was a bit of a 'head' where the click rivet was peened that would snag the spring at one point. I'll also look for any 'stiff section' although I believe this was a new German spring that I installed and it initially looked good. I also had one case where the outer coil of the spring was rising up on the rounded bottom of the spring box can.

    Dave

    The 48N has those fixed spring box cans and there is pretty good separation between the time and strike trains, but the thought that something in the strike train could cause the problem is an interesting one. Perhaps the strike train is failing to run occasionally? There are so many clocks around here that I wouldn't notice. When it runs down I count the winding turns on the strike side to see if it has been keeping up, although I have heard it strike periodically when in that room.

    RC 314820.jpg
     
  11. dad1891

    dad1891 Registered User

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    In retrospect, I probably should have mentioned that I would also look higher up in the train to see if two wheels were interfering with each other. The problem with the clock that I described was there was slight runout or "wobble" in the two wheels and they wouldn't cause any problem until both "wobbles" lined up with each other. It would only happen every week or two. The thing that really irritated me is after I found the problem, I disassembled the movement and there was a shiny spot where the rub was. I felt pretty stupid.
     
  12. Willie X

    Willie X Registered User

    Feb 9, 2008
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    RC,
    It's going to be something weird. A lot of good stuff already mentioned. I can think of a few more things like: a pivot hole with a sharp inside edge, slightly bent pivot, slightly bent or deformed tooth or trundle, tapered pivot, big radius where a pivot meets the arbor, slightly bent arbor, wheel mounted off center, I'm guessing you already removed the motion works as a test ... I've seen some really odd things happen with those little motion works gears.
    Could be something simple, like a to tight crutch loop!
    Good luck,
    Willie X
     
  13. R. Croswell

    R. Croswell Registered User

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    Yeah, gotta spend a lot time checking all the usual suspects and all the other stuff that's been mentioned. Don't mind feeling stupid if I find the problem. Can't say what it isn't until I find what it is.

    RC
     
  14. R. Croswell

    R. Croswell Registered User

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    That's something easily overlooked and I'll be sure to check it on the 48N. I also have a ST-124 that I just finished on the test rack that was having similar problems. It somehow didn't sound just right and would occasionally stop. The verge pivot hole was a little loose but I initially thought not that bad, but with your suggestion fresh on my mind I went back and bushed it anyway and checked that it was locking properly after the bushing installation. It now sounds normal is running strong and hasn't stopped......so far. The 124 can have a mind of its own but I think this one is now good to go. Thanks for the suggestion. Now if the fix for the 48N could be so simple.

    RC
     
  15. Bruce Alexander

    Bruce Alexander Registered User
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    Kinsler's tip is a good one I think. I had a similar problem with a S.T. Kaiser 15-day movement. Everything looked good to me on my first pass. There was a little "slop" in the Verge Bushings, but not enough to really draw my attention/concern. Intermittent stalling was the result of my oversight. Went back and bushed both Verge Pivots and it hasn't stalled since. Probably about 5 years ago? It's been a little while.

    As you mentioned RC, a much more robust action and sound once the loss/waste of power was eliminated. I don't overlook Verge Pivots anymore.

    Good luck.
     
  16. Tinker Dwight

    Tinker Dwight Registered User

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    Recoils are more forgiving of loose verge pivots but deadbeats need close
    tolerances.
    Tinker Dwight
     
  17. R. Croswell

    R. Croswell Registered User

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    That does in deed seem to be the case, especially in clocks like this that are not grossly over-powered like many common recoil movements.

    So the patient has stopped this morning on the 10th day. At least we know the spring is long enough and strong enough to power this clock beyond 8-days. Of course we both know that springs are seldom a problem as long as they are not broken. I hope to dig deeper into this one next week.

    RC
     
  18. Bruce Alexander

    Bruce Alexander Registered User
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    It may not just be one issue but one or more marginal issues which come together periodically to cause stalling. Perhaps it occurs when the time train is in some stage of activation the strike train or there's a strike train related drag on the time train. The decreasing torque curve of a perfectly fine mainspring (even brand new mainsprings have a torque "curve") might help to expose the intermittent issue a few or more days after a full wind. Just another possibility as you work through and eliminate them.
     
  19. Karl Thies

    Karl Thies Registered User
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    #19 Karl Thies, Apr 24, 2018
    Last edited: Apr 24, 2018
    Did you replace both springs with the same size spring? From my experience, the strike side uses a 3/4" x .016" x 60", and the time side uses a 3/4" x .012" x 90". The shorter and stronger spring could be causing the problem. I realize this is an old thread. Hope you have found your answer to the problem.
     
  20. R. Croswell

    R. Croswell Registered User

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    Yes this is an old thread, thank you for your interest. I did in fact replace the main springs the same as you suggested. I determined that there was no end shake on T1 and T2 and I felt that perhaps the T3 bushing was a bit tight, and I gave the verge a bit more lock. On this model there is a steel leaf that presses against and loads the center shaft I assume to keep the minute hand from showing any slack motion. That leaf had become rough and roughed up the arbor causing excess friction. That was cleaned up, the arbor polished, the tension on that leaf reduced and it was lubricated with synthetic grease at that point. The clock ran fine after that and was returned to the owner and I haven't heard any more. I assume it is doing fine.

    RC
     
  21. Karl Thies

    Karl Thies Registered User
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    Thanks for the update, glad you found the problem.
     
  22. bikerclockguy

    bikerclockguy Registered User
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    I didn't put the pencil to this, but does each wheel mesh with the others in all possible combinations in a 4 day period? In other words, if you numbered the teeth and the pinions in the lantern on each wheel, would tooth 24 on wheel 1 be meshed with pinion 3 on wheel 2 when pinion 5 on wheel 2 is meshed with tooth 18 on wheel 3, etc? Just thinking that if something is just a little off, a barely bent arbor or something, it might take that long to hit the right combination where there isn't enough slack in the rest of the train to compensate for it.
     
  23. R. Croswell

    R. Croswell Registered User

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    I have no idea how long it would take for every possible tooth combination to come up. I usually test run repaired clocks for two weeks. This is an old thread and the clock has been out almost a year and as far as I know it is doing fine.

    RC
     
    Bujumon likes this.
  24. bikerclockguy

    bikerclockguy Registered User
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    Well, I'm glad it's up and running anyway. I was thinking along the lines of 2 small irregularities that had to line up together to stop it. The 4-day cycle just made me lean toward that. My box clock project turned out well. Still not sure why that guy went with the offset bushing when it lined up so well with a normal, centered bushing, but it's running strong, so that's good enough for me. Also, you gave me some advice on the fly on a bim-bam clock a few months ago, and I wanted to let you know that was right on the money. The strike/chime(whatever you call it on those)would start slow and then get fast and slow down again.You said the fly acts like a clutch and has to be tight enough to slow down the train and loose enough to slip a little at the end of the cycle to absorb the momentum. I played with it for a bit and couldn't get it quite right, and instead of walking away from it for a bit I went with the advice of the dissenters who said it didn't make any difference, and they were dead wrong. I JB welded it to the arbor, and when the strike stopped, it sounded like you had shut the drawer on one of those old metal cash registers. I only let it do that twice(had to be sure the first wasn't just a fluke)and then shelved it. I got it back out last night, and used my hot air solder station at 640 degrees to get the JB off. Then I took my time and got a nice snug-but-not-tight fit in the groove on the arbor, and it's running great too!
     
  25. R. Croswell

    R. Croswell Registered User

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    Biker, glad it all turned well with yours as well. For those elusive stopping problems I mark each wheel/piniion where it stops and look for two marks that line up the next time it stops and that's where the trouble is if it is a tooth problem.

    RC
     
  26. bikerclockguy

    bikerclockguy Registered User
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    Sounds like a good system. So you mark each one at the point where they mesh, and with the ratios all being different it's highly unlikely that another set of marks will be lined up when the pair that's a problem intersect with each other again. I'll definitely keep that one in my bag of tricks; the thing I like best about it is the clock does all the work, and you don't drive yourself crazy trying to find it. Thanks, RC!
     

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